Urinary aldehydes as indicators of lipid peroxidation in vivo

Development and evaluation of a liquid chromatography-tandem mass spectrometry method for simultaneous measurement of toxic aldehydes from brain tissue

Reactive aldehydes are a class of electrophilic low molecular weight compounds that play an essential role in physiological function and lipid peroxidation. These molecules are implicated in many diseases, especially cardiovascular and neurodegenerative diseases, and are potential endogenous markers of lipid peroxidation. However, there are limited options to accurately quantify multiple reactive aldehydes in brain tissue. This study developed and validated a 3-nitrophenylhydrazine derivatization-based LC-MS/MS method to quantify four reactive aldehydes: malondialdehyde, acrolein, 4-hydroxy-2-hexenal and 4-hydroxy-2-nonenal. Method development involved comparing the sensitivity of detection between widely used derivatization reagents: 2,4-dinitrophenylhydrazine and 3-nitrophenylhydrazine. Our data showed that 3-nitrophenylhydrazine resulted in greater sensitivity. Additional method development included evaluation of hydrolysis sample pretreatment, selection of protein precipitation reagent, and optimization of derivatization conditions. The optimized conditions included no hydrolysis and use of 20 % trichloroacetic acid as the protein precipitation reagent. The optimized derivatization condition was 25 mM 3-nitrophenylhydrazine reacted at 20 °C for 30 min. The chromatographic conditions were optimized to reduce matrix effects, ion suppression, and efficient analysis time (<7-minute analytical run). The four aldehyde species were accurately quantified in brain tissue using stable-labeled internal standards. Application of this assay to a traumatic brain injury mouse model revealed significant accumulation of acrolein, 4-hydroxy-2-hexenal, and 4-hydroxy-2-nonenal at 28 days post injury. Overall, a validated method was developed to rapidly quantify the most prominent reactive aldehydes associated with lipid peroxidation during injury progression following acute brain trauma.

A Review of Oxidative Stress Products and Related Genes in Early Alzheimer's Disease

Oxidative stress is associated with the progression of Alzheimer’s disease (AD). Reactive oxygen species can modify lipids, DNA, RNA, and proteins in the brain. The products of their peroxidation and oxidation are readily detectable at incipient stages of disease. Based on these oxidation products, various biomarker-based strategies have been developed to identify oxidative stress levels in AD. Known oxidative stress-related biomarkers include lipid peroxidation products F2-isoprostanes, as well as malondialdehyde and 4-hydroxynonenal which both conjugate to specific amino acids to modify proteins, and DNA or RNA oxidation products 8-hydroxy-2’-deoxyguanosine (8-OHdG) and 8-hydroxyguanosine (8-OHG), respectively. The inducible enzyme heme oxygenase type 1 (HO-1) is found to be upregulated in response to oxidative stress-related events in the AD brain. While these global biomarkers for oxidative stress are associated with early-stage AD, they generally poorly differentiate from other neurodegenerative disorders that also coincide with oxidative stress. Redox proteomics approaches provided specificity of oxidative stress-associated biomarkers to AD pathology by the identification of oxidatively damaged pathology-specific proteins. In this review, we discuss the potential combined diagnostic value of these reported biomarkers in the context of AD and discuss eight oxidative stress-related mRNA biomarkers in AD that we newly identified using a transcriptomics approach. We review these genes in the context of their reported involvement in oxidative stress regulation and specificity for AD. Further research is warranted to establish the protein levels and their functionalities as well as the molecular mechanisms by which these potential biomarkers are involved in regulation of oxidative stress levels and their potential for determination of oxidative stress and disease status of AD patients.

Lipid Peroxidation in Atherosclerotic Cardiovascular Diseases

Significance: Atherosclerotic cardiovascular diseases (ACVDs) continue to be a primary cause of mortality worldwide in adults aged 35-70 years, occurring more often in countries with lower economic development, and they constitute an ever-growing global burden that has a considerable socioeconomic impact on society. The ACVDs encompass diverse pathologies such as coronary artery disease and heart failure (HF), among others. Recent Advances: It is known that oxidative stress plays a relevant role in ACVDs and some of its effects are mediated by lipid oxidation. In particular, lipid peroxidation (LPO) is a process under which oxidants such as reactive oxygen species attack unsaturated lipids, generating a wide array of oxidation products. These molecules can interact with circulating lipoproteins, to diffuse inside the cell and even to cross biological membranes, modifying target nucleophilic sites within biomolecules such as DNA, lipids, and proteins, and resulting in a plethora of biological effects. Critical Issues: This review summarizes the evidence of the effect of LPO in the development and progression of atherosclerosis-based diseases, HF, and other cardiovascular diseases, highlighting the role of protein adduct formation. Moreover, potential therapeutic strategies targeted at lipoxidation in ACVDs are also discussed. Future Directions: The identification of valid biomarkers for the detection of lipoxidation products and adducts may provide insights into the improvement of the cardiovascular risk stratification of patients and the development of therapeutic strategies against the oxidative effects that can then be applied within a clinical setting.

Total Antioxidant Capacity, Catalase Activity and Salivary Oxidative Parameters in Patients with Temporomandibular Disorders

Objectives:

Temporomandibular disorders (TMD) are characterized by pain or discomfort in the temporomandibular joint, periauricular region, masticatory muscles, and neck on one or both sides. It may also be associated with joint sounds, restricted mandibular movements and mandibular deviation. Oxidative agents may have a deleterious role in the pathogenesis of joint diseases, and oxidative stress can lead to TMD. The aim of this study was to assess the oxidative stress biomarkers in the saliva of TMD patients and healthy controls.

Materials and Methods:

This case-control study was conducted on 30 patients with TMDs (5 males and 25 females) with a mean age of 30.7±13.2 years, and 30 healthy controls (5 males and 25 females) with a mean age of 29.16±11.2 years. Saliva samples were collected according to the standard protocol and the total antioxidant capacity of the saliva (non-enzymatic), catalase activity, and malondialdehyde (MDA) levels were measured using the ferric reducing ability of plasma, Aebi’s method, and high-performance liquid chromatography, respectively. Finally, The MDA levels were analyzed by the Mann-Whitney test. Other quantitative parameters were analyzed by independent t-test.

Results:

TMD patients had significantly higher salivary levels of MDA compared to the control group (P=0.001). But there were no significant differences in catalase (P=0.49) and total antioxidant capacity (P=0.22) of TMD patients and healthy controls.

Conclusion:

It seems that oxidative stress may be involved in the pathogenesis of TMDs.

Characterization of Antioxidant Potential of Seaweed Extracts for Enrichment of Convenience Food

In recent years, there has been a growing interest in natural antioxidants as replacements of synthetic compounds because of increased safety concerns and worldwide trend toward the usage of natural additives in foods. One of the richest sources of natural antioxidants, nowadays largely studied for their potential to decrease the risk of diseases and to improve oxidative stability of food products, are edible brown seaweeds. Nevertheless, their antioxidant mechanisms are slightly evaluated and discussed. The aims of this study were to suggest possible mechanism(s) of Fucus vesiculosus antioxidant action and to assess its bioactivity during the production of enriched rye snacks. Chemical and cell-based assays indicate that the efficient preventive antioxidant action of Fucus vesiculosus extracts is likely due to not only the high polyphenol content, but also their good Fe²⁺-chelating ability. Moreover, the data collected during the production of Fucus vesiculosus-enriched rye snacks show that this seaweed can increase, in appreciable measure, the antioxidant potential of enriched convenience cereals. This information can be used to design functional foods enriched in natural antioxidant ingredients in order to improve the health of targeted consumers.

Environmental impact on the onset of hypertension-induced end-stage renal disease

This study intends to assess the impact of environmental factors on the onset of hypertension-induced end-stage renal disease (ESRD) and to compare the level of oxidative stress with nonhypertensive diabetic ESRD. ESRD patients were evaluated along with healthy controls through questionnaire for demographic, nutritional and lifestyle variables. Oxidants were measured along with antioxidants. Multiple linear regression (MLR) models were applied to analyze association of studied variables with oxidants and antioxidants. Most of the hypertensive nephrosclerotic patients were residing in locality that was either closer to industrial belt or polluting water bodies, belonging to low socioeconomic status that invariably affected their lifestyle and nutritional status. Hypertensive ESRD patients showed more pronounced oxidative stress than diabetic ESRD. Several of the studied variables were significantly associated with oxidants and antioxidants. Demographic, nutritional and lifestyle variables appeared to have suggestive effect on the onset of hypertensive nephrosclerosis.

Influence of feeding thermally peroxidized soybean oil on growth performance, digestibility, and gut integrity in finishing pigs

Consumption of peroxidized lipids has been shown to reduce pig performance and energy and lipid digestibility. Objectives of the current study were to evaluate the effect of feeding soybean oil (SO) with different levels of peroxidation on growth performance, lipid, N, and GE digestibility, plasma Trp, and gut integrity in finishing pigs. Fifty-six barrows (46.7 ± 5.1 kg initial BW) were randomly assigned to one of four diets in each of two dietary phases, containing either 10% fresh SO (22.5 °C) or thermally processed SO (45 °C for 288 h, 90 °C for 72 h, or 180 °C for 6 h), each infused with of 15 L/min of air. Peroxide values were 2.0, 17.4, 123.6, and 19.4 mEq/kg; 2,4-decadienal values were 2.07, 1.90, 912.15, and 915.49 mg/kg; and 4-hydroxynonenal concentrations were 0.66, 1.49, 170.48, and 82.80 mg/kg, for the 22.5, 45, 90, and 180 °C processed SO, respectively. Pigs were individually housed and fed ad libitum for 81 d to measure growth performance, including a metabolism period to collect urine and feces for determination of GE, lipid, N digestibility, and N retention. Following the last day of fecal and urine collection when pigs were in the metabolism crates, lactulose and mannitol were fed and subsequently measured in the urine to evaluate gut permeability, while markers of oxidative stress were evaluated in plasma, urine, and liver. There were no differences observed in ADFI (P = 0.91), but average daily gain (ADG) and gain:feed G:F were decreased in pigs fed 90 °C SO diet (P ≤ 0.07) compared to pigs fed the other SO diets. Pigs fed the 90 and 180 °C SO had the lowest (P = 0.05) DE as a % of GE compared to pigs fed the 22.5 °C SO, with pigs fed the 45 °C SO being intermediate. Lipid digestibility was similarly affected (P = 0.01) as energy digestibility, but ME as a % of DE was not affected by dietary treatment (P = 0.16). There were no effects of lipid peroxidation on N digested, N retained, or the urinary lactulose:mannitol ratio (P ≥ 0.25). Pigs fed the SO processed at 90 and 180 °1C had lower concentrations (P < 0.01) of plasma Trp compared to pigs fed the 22.5 and 45 °C SO treatments. Pigs fed 90 °C SO had the greatest (P < 0.01) concentrations of F2-isoprostane in plasma and urine thiobarbituric acid reactive substances compared to the other SO treatments. These results indicate that the change in FA composition and/or the presence of lipid peroxidation products in peroxidized SO may reduce ADG, G:F, and digestibility of GE and ether extract, but has little impact on N digestibility and balance or on gut permeability.

Relationship between free and total malondialdehyde, a well-established marker of oxidative stress, in various types of human biospecimens

BACKGROUND

Oxidative stress is involved in thoracic diseases and health responses to air pollution. Malondialdehyde (MDA) is a well-established marker of oxidative stress, but it may be present in unconjugated and conjugated forms. To our knowledge, no studies have conducted a systemic evaluation of both free MDA (unconjugated MDA) and total MDA (the sum of both unconjugated and conjugated MDA) across various types of human biospecimens.

METHODS

Free MDA and total MDA were simultaneously measured in a range of human biospecimens, including nasal fluid (N=158), saliva (N=158), exhaled breath condensate (N=40), serum (N=232), and urine (N=429). All samples were analyzed using an HPLC-fluorescence method with high sensitivity and specificity. Due to the right skewed distribution of free MDA and total MDA, we performed natural-log transformation before subsequent statistical analyses. The relationship between the natural log of free and total MDA was evaluated by R2 of simple linear regression. T test was used for comparisons of means between two groups. One-way analysis of variance was used in combination with Tukey's test to compare the natural log of the ratio of free MDA to total MDA across various types of biospecimens.

RESULTS

For exhaled breath condensate, serum, urine, nasal fluid and saliva samples, the R2 between free and total MDA were 0.61, 0.22, 0.59, 0.47 and 0.06, respectively; the medians of the free MDA to total MDA ratio were 48.1%, 17.4%, 9.8%, 5.1% and 3.0%, respectively; the free MDA to total MDA ratio in EBC > serum > urine > nasal fluid > saliva (P<0.001 for pairwise comparisons).

CONCLUSIONS

For exhaled breath condensate and urine samples, using either free or total MDA can provide information regarding the level of oxidative stress; however, that is not the case for serum, nasal fluid, and saliva given the low correlations between free and total MDA.

Astaxanthin counteracts the effects of heat shock on the maturation of bovine oocytes

The cellular mechanisms induced by elevated temperature on oocytes are not fully understood. However, there is evidence that some of the deleterious effects of heat shock are mediated by a heat-induced increase in reactive oxygen species (ROS). In this context, carotenoid antioxidants might have a thermoprotective effect. Therefore, the objective of this study was to determine the role of astaxanthin (AST) on oocyte ROS production and on the redox profile and developmental competency of cumulus-oocyte complexes (COCs) after 14 h heat shock (41°C) during in vitro maturation (IVM). Exposure of oocytes to heat shock during IVM increased ROS and reduced the ability of the oocyte to cleave and develop to the blastocyst stage. However, 12.5 and 25 nM astaxanthin rescued these negative effects of heat shock; astaxanthin counteracted the heat shock-induced increase in ROS and restored oocyte developmental competency. There was no effect of astaxanthin on maturation medium lipid peroxidation or on glutathione peroxidase and catalase activity in oocytes and cumulus cells. However, astaxanthin stimulated superoxide dismutase (SOD) activity in heat-shocked cumulus cells. In conclusion, direct heat shock reduced oocyte competence, which was restored by astaxanthin, possibly through regulation of ROS and SOD activity in oocytes and COCs.

Urinary Volatile Organic Compounds as Potential Biomarkers in Idiopathic Membranous Nephropathy

OBJECTIVE

To detect urinary volatile organic compounds (VOCs) in patients with idiopathic membranous nephropathy (iMN) and normal controls, and to examine whether or not urinary VOCs can act as biomarkers for the diagnosis of iMN independent of renal biopsy.

MATERIALS AND METHODS

Gas chromatography/mass spectrometry (GC/MS) was used to assess the urine collected from 63 iMN patients and 15 normal controls. The statistical methods of principal component analysis and partial least squares discriminant analysis were performed to process the final data in Common Data Format which were converted from GC/MS data.

RESULTS

Six VOCs in the urine samples of iMN patients exhibited significant differences from those of normal controls: carbamic acid monoammonium salt, 2-pentanone, 2,4-dimethyl-pentanal, hydrogen azide, thiourea, and 4-heptanone were significantly higher than in controls (p < 0.05).

CONCLUSIONS

Six urinary VOCs were isolated from patients with iMN using GC/MS. The analysis of urinary VOCs using GC/MS could be developed into a non-invasive method for the detection of iMN.

The importance of antioxidants which play the role in cellular response against oxidative/nitrosative stress: current state

Remarkable interest has risen in the idea that oxidative/nitrosative stress is mediated in the etiology of numerous human diseases. Oxidative/Nitrosative stress is the result of an disequilibrium in oxidant/antioxidant which reveals from continuous increase of Reactive Oxygen and Reactive Nitrogen Species production. The aim of this review is to emphasize with current information the importance of antioxidants which play the role in cellular responce against oxidative/nitrosative stress, which would be helpful in enhancing the knowledge of any biochemist, pathophysiologist, or medical personnel regarding this important issue. Products of lipid peroxidation have commonly been used as biomarkers of oxidative/nitrosative stress damage. Lipid peroxidation generates a variety of relatively stable decomposition end products, mainly α, β-unsaturated reactive aldehydes, such as malondialdehyde, 4-hydroxy-2-nonenal, 2-propenal (acrolein) and isoprostanes, which can be measured in plasma and urine as an indirect index of oxidative/nitrosative stress. Antioxidants are exogenous or endogenous molecules that mitigate any form of oxidative/nitrosative stress or its consequences. They may act from directly scavenging free radicals to increasing antioxidative defences. Antioxidant deficiencies can develop as a result of decreased antioxidant intake, synthesis of endogenous enzymes or increased antioxidant utilization. Antioxidant supplementation has become an increasingly popular practice to maintain optimal body function. However, antoxidants exhibit pro-oxidant activity depending on the specific set of conditions. Of particular importance are their dosage and redox conditions in the cell.

Protective effect of two essential oils isolated from Rosa damascena Mill. and Lavandula angustifolia Mill, and two classic antioxidants against L-dopa oxidative toxicity induced in healthy mice

Levodopa (L-dopa) is a "gold standard" and most effective symptomatic agent in the Parkinson's disease (PD) treatment. The several treatments have been developed in an attempt to improve PD treatment, but most patients were still levodopa dependent. The issue of toxicity was raised in vitro studies, and suggests that L-dopa can be toxic to dopaminergic neurons, but it is not yet entirely proven. L-dopa prolonged treatment is associated with motor complications and some limitations. Combining the L-dopa therapy with antioxidants can reduce related sideeffects and provide symptomatic relief. The natural antioxidants can be isolated from any plant parts such as seeds, leaves, roots, bark, etc., and their extracts riched in phenols can retard the oxidative degradation of the lipids, proteins and DNA. Thus, study suggests that combination of essential oils (Rose oil and Lavender oil), Vitamin C and Trolox with Ldopa can reduce oxidative toxicity, and may play a key role in ROS/RNS disarm.

Elevated urinary excretion of aluminium and iron in multiple sclerosis

Multiple sclerosis (MS) is a chronic, immune-mediated, demyelinating disease of the central nervous system of as yet unknown aetiology. A consensus of opinion has suggested that the disorder is the result of an interplay between environmental factors and susceptibility genes. We have used a battery of analytical techniques to determine if the urinary excretion of i) markers of oxidative damage; ii) iron and iii) the environmental toxin aluminium and its antagonist, silicon, are altered in relapsing remitting (RRMS) and secondary progressive MS (SPMS). Urinary concentrations of oxidative biomarkers, MDA and TBARS, were not found to be useful indicators of inflammatory disease in MS. However, urinary concentrations of another potential marker for inflammation and oxidative stress, iron, were significantly increased in SPMS ( P<0.01) and insignificantly increased in RRMS ( P>0.05). Urinary concentrations of aluminium were also significantly increased in RRMS ( P<0.001) and SPMS ( P<0.05) such that the levels of aluminium excretion in the former were similar to those observed in individuals undergoing metal chelation therapy. The excretion of silicon was lower in MS and significantly so in SPMS ( P<0.05). Increased excretion of iron in urine supported a role for iron dysmetabolism in MS. Levels of urinary aluminium excretion similar to those seen in aluminium intoxication suggested that aluminium may be a hitherto unrecognized environmental factor associated with the aetiology of MS. If aluminium is involved in MS then an increased dietary intake of its natural antagonist, silicon, might be a therapeutic option.

Malondialdehyde Epitopes as Targets of Immunity and the Implications for Atherosclerosis

Accumulating evidence suggests that oxidation-specific epitopes (OSEs) constitute a novel class of damage-associated molecular patterns (DAMPs) generated during high oxidative stress but also in the physiological process of apoptosis. To deal with the potentially harmful consequences of such epitopes, the immune system has developed several mechanisms to protect from OSEs and to orchestrate their clearance, including IgM natural antibodies and both cellular- and membrane-bound receptors. Here, we focus on malondialdehyde (MDA) epitopes as prominent examples of OSEs that trigger both innate and adaptive immune responses. First, we review the mechanisms of MDA generation, the different types of adducts on various biomolecules and provide relevant examples for physiological carriers of MDA such as apoptotic cells, microvesicles, or oxidized low-density lipoproteins. Based on recent insights, we argue that MDA epitopes contribute to the maintenance of homeostatic functions by acting as markers of elevated oxidative stress and tissue damage. We discuss multiple lines of evidence that MDA epitopes are proinflammatory and thus important targets of innate and adaptive immune responses. Finally, we illustrate the relevance of MDA epitopes in human pathologies by describing their capacity to drive inflammatory processes in atherosclerosis and highlighting protective mechanisms of immunity that could be exploited for therapeutic purposes.

The antioxidant effects of pomegranate extract on local and remote organs in a mesenteric ischemia and reperfusion model

OBJECTIVES

We investigated whether pomegranate extract plays a protective antioxidant role against mesenteric ischemia-reperfusion injury (IR), which can lead to a systemic response and damage distant organs, such as the lung, liver, and kidney.

METHODS

Forty female Wistar-Albino rats were separated into four groups: laparotomy, laparotomy + PG, mesenteric IR, and mesenteric IR and pomegranate (IR + PG). In the laparotomy + PG and IR + PG groups, pomegranate (225 mg/kg) was given by oral gavage at the beginning of the study. Ischemia was induced for 30 minutes, and reperfusion was subsequently allowed for 60 minutes in the IR and IR + PG groups. The malondialdehyde (MDA) and total antioxidant activity (AOA) levels were evaluated in blood samples. Additionally, all tissues were removed for the measurement of AOA and total oxidant status as well as for subsequent histopathological evaluation. The oxidative stress index was calculated.

RESULTS

Histopathological changes in all organs were significantly higher in the IR group and significantly lower in the IR + PG group vs. the other groups. Serum MDA levels were significantly lower in the IR + PG group than in the IR group. No significant difference was found in AOA levels of the groups.

DISCUSSION

These data may explain the positive protective effects of pomegranate based on the histopathologic findings in ischemic conditions in an intestinal IR injury model.

Lipoprotein-associated oxidative stress: a new twist to the postprandial hypothesis

Oxidative stress is recognized as one of the primary processes underlying the initiation and progression of atherosclerotic vascular disease. Under physiological conditions, the balance between reactive oxygen species (ROS) generation and ROS scavenging is tightly controlled. As part of normal cellular metabolism, regulated oxidative stress is responsible for a variety of cellular responses. Excess generation of ROS that could not be compensated by antioxidant system has been suggested to be responsible for a number of pathological conditions. Due to their short biological half-lives, direct measurement of ROS is not available and surrogate measures are commonly used. Plasma lipoproteins, by virtue of their close interactions with endothelial cells in the vasculature and the susceptibility of their surface lipids to oxidative modification, are perfect biological sensors of oxidative stress in the arterial wall. In particular, with each consumed meal, triglyceride-rich lipoproteins, secreted by the intestine into the circulation, are responsible for the delivery of 20–40 grams of fat to the peripheral tissues. This flux of dietary lipids is accompanied by concomitant increases in glucose, insulin and other meal-associated metabolites. The contribution of postprandial lipemia to the pathogenesis of atherosclerosis has been previously suggested by several lines of investigation. We have extended this hypothesis by demonstrating the acute generation of oxidative epitopes on plasma lipoproteins as well as transient changes in the oxidative susceptibility of plasma lipoproteins.

Oxidative status in different settings and with different methodological approaches compared by Receiver Operating Characteristic curve analysis

OBJECTIVES

To test the performance of different analytical approaches in highlighting the occurrence of deregulated redox status in various physio-pathological situations.

DESIGN AND METHODS

35 light and 61 heavy smokers, 19 chronic renal failure, 59 kidney transplanted patients, and 87 healthy controls were retrospectively considered for the study. Serum oxidative stress and antioxidant status, assessed by spectrophotometric Reactive Oxygen Metabolites (d-ROMs) and Total Antioxidant Capacity (TAC) tests, respectively, were compared with plasma free (F-MDA) and total (T-MDA) malondialdehyde, both quantified by isotope-dilution-gas chromatography-mass spectrometry (ID-GC-MS). Sensitivity, specificity and cut-off points of T-MDA, F-MDA, d-ROMs and TAC were evaluated by both Receiver Operating Characteristic (ROC) analyses and area under the ROC curve (AUC).

RESULTS

Only T-MDA assay showed a clear absence of oxidative stress in controls and significant increase in all patients (AUC 1.00, sensitivity and specificity 100%). Accuracy was good for d-ROMs (AUC 0.87, sensitivity 72.8%, specificity 100%) and F-MDA (AUC 0.82, sensitivity 74.7%, specificity 83.9%), but not high enough for TAC to show in patients impaired antioxidant defense (AUC 0.66, sensitivity 52.0%, specificity 92.9%).

CONCLUSIONS

This study reveals T-MDA as the best marker to detect oxidative stress, shows the ability of d-ROMs to identify modified oxidative status particularly in the presence of high damages, and evidences the poor TAC performance. d-ROMs and TAC assays could be useful for routine purposes; however, for an accurate clinical data evaluation, their comparison versus a "gold standard method" is required.

The protective effects of pomegranate extracts against renal ischemia-reperfusion injury in male rats

Aim:

To evaluate the possible protective effect of pomegranate extract (PE) on rats following renal ischemia–reperfusion (I/R) injury.

Materials and Methods:

Twenty-four Wistar rats were divided into three groups. Sham group underwent laparotomy then waited for 45 minutes without ischemia. I/R group were subjected to left renal ischemia for 45 minutes followed by 60 minutes of reperfusion. I/R + PE group were subjected to the same renal I/R as the I/R group were also given 225 mg/kg PE peroral 30 minutes prior to the ischemia. Malondialdehyde (MDA), total antioxidant capacity (TAC), total oxidant status (TOS), and oxidative stress index (OSI) were determined on the blood samples and kidney tissues. Histopathological analyses were conducted on the kidney tissues.

Results:

Serum TAC levels were significantly decreased in I/R group when compared with S group (P = 0.001). Serum MDA levels were increased in I/R group; however, it was not statistically significant. In rat kidney tissues, TOS levels and OSI index were significantly increased after I/R injury, while TAC levels were decreased. In I/R + PE group, PE reversed the negative effects of I/R injury. PE pretreatment was effective in decreasing tubular necrosis score.

Conclusion:

PE pretreatment ameliorated the oxidative damage and histopathological changes occurring following renal I/R injury.

2-Hydrazinoquinoline as a Derivatization Agent for LC-MS-Based Metabolomic Investigation of Diabetic Ketoacidosis

Short-chain carboxylic acids, aldehydes and ketones are products and regulators of many important metabolic pathways. Their levels in biofluids and tissues reflect the status of specific metabolic reactions, the homeostasis of the whole metabolic system and the wellbeing of a biological entity. In this study, the use of 2-hydrazinoquinoline (HQ) as a novel derivatization agent was explored and optimized for simultaneous liquid chromatography-mass spectrometry (LC-MS) analysis of carboxylic acids, aldehydes and ketones in biological samples. The formation of carboxylic acid derivative is attributed to the esterification reaction between HQ and a carboxyl group, while the production of aldehyde and ketone derivatives is through the formation of Schiff bases between HQ and a carbonyl group. The compatibility of HQ with biological samples was demonstrated by derivatizing urine, serum and liver extract samples. Using this HQ-based approach, the kinetics of type 1 diabetes-induced metabolic changes was characterized by the LC-MS-based metabolomic analysis of urine samples from streptozotocin (STZ)-treated mice. Subsequently, carboxylic acid, aldehyde and ketone metabolites associated with STZ-elicited disruption of nutrient and energy metabolism were conveniently identified and elucidated. Overall, HQ derivatization of carboxylic acids, aldehydes and ketones could serve as a useful tool for the LC-MS-based metabolomic investigation of endogenous metabolism.

Measurement of total and free malondialdehyde by gas-chromatography mass spectrometry--comparison with high-performance liquid chromatography methology

Malondialdehyde (MDA) is considered to be a biomarker for enzymatic degradation and lipid peroxidation of polyunsaturated fatty acids. Usually, MDA determination from different biological materials is performed by reaction with thiobarbituric acid (TBA) followed by high-performance liquid chromatography (HPLC) analysis and fluorometric detection. As this method lacks specificity and sensitivity, we developed a gas chromatography-mass spectrometry (GC-MS) method based on derivatization of MDA with 2,4-dinitrophenylhydrazine. Representative ions in negative ion chemical ionization (NICI) mode were recorded at m/z 204 for MDA and at m/z 206 for the deuterated analogon (MDA-d₂) as internal standard. This stable and precise GC-MS method showed good linearity (r² = 0.999) and higher specificity and sensitivity than the HPLC method and was validated for both total MDA (t-MDA) and free MDA (f-MDA). Within-day precisions were 1.8-5.4%, between-day precisions were 4.8-9.2%; and accuracies were between 99% and 101% for the whole calibration range (0.156-5.0 μmol/L for t-MDA and 0.039-0.625 μmol/L for f-MDA). Although comparison of t-MDA levels from GC-MS and HPLC results using Passing-Bablok regression analysis as well as Bland-Altman plot showed a correlation of the data, a tendency to increased results for the HPLC values was detectable, due to possible formation of unspecific products of the TBA reaction.

Ellagic acid ameliorates lung injury after intestinal ischemia-reperfusion

Background:

The aim of this study was to investigate the possible protective role of antioxidant treatment with ellagic acid (EA) on lung injury after intestinal ischemia-reperfusion (I/R) injury using biochemical and histopatological approaches.

Materials and Methods:

Forty rats were divided into four groups as control, control + EA, I/R, and I/R + EA. The control and control + EA groups were also anesthetized and subjected to laparotomy, but without clamp application. The control + EA and I/R + EA groups were given EA (85 mg/kg) orally prior to experiment. The I/R and I/R + EA groups underwent 30 minutes of intestinal ischemia and 1 hour of reperfusion. In all groups, serum total antioxidant capacity (TAC) and malondialdehyde (MDA) levels were determined. TAC, total oxidative status (TOS), and oxidative stress index (OSI) in lung tissue were measured. Lung tissue histopathology was also evaluated by light microscopy.

Results:

TAC levels were higher in control, EA, and I/R + EA groups while TOS, OSI, and MDA levels were lower in these groups compared with I/R group. Serum MDA levels were significantly higher in I/R + EA group than that of control group. Lung tissue TAC levels were lower in I/R + EA group while OSI values were higher in that groups compared with EA group. Histological tissue damage was milder in the EA treatment group than in the I/R group.

Conclusion:

These results suggest that EA treatment protected the rats lung tissue against intestinal I/R injury.

Application of medical and analytical methods in Lyme borreliosis monitoring

Lyme borreliosis (LB) is one of the most common tick-borne diseases in the northern hemisphere. It is a chronic inflammatory disease caused by the spirochaete Borrelia burgdorferi. In its early stages, pathological skin lesions, namely erythema chronicum migrans, appear. The lesions, usually localised at the site of the bite, may become visible from a few weeks up to 3 months after the infection. Predominant clinical symptoms of the disease also involve joint malfunctions and neurological or cardiac disorders. Lyme disease, in all its stages, may be successfully treated with antibiotics. The best results, however, are obtained in its early stages. In order to diagnose the disease, numerous medical or laboratory techniques have been developed. They are applied to confirm the presence of intact spirochaetes or spirochaete components such as DNA or proteins in tick vectors, reservoir hosts or patients. The methods used for the determination of LB biomarkers have also been reviewed. These biomarkers are formed during the lipid peroxidation process. The formation of peroxidation products generated by human organisms is directly associated with oxidative stress. Apart from aldehydes (malondialdehyde and 4-hydroxy-2-nonenal), many other unsaturated components such as isoprostenes and neuroprostane are obtained. The fast determination of these compounds in encephalic fluid, urine or plasma, especially in early stages of the disease, enables its treatment. Various analytical techniques which allow the determination of the aforementioned biomarkers have been reported. These include spectrophotometry as well as liquid and gas chromatography. The analytical procedure also requires the application of a derivatization step by the use of selected reagents.

Effects of encapsulated fruit and vegetable juice powder concentrates on oxidative status in heavy smokers

OBJECTIVE

Long-term cigarette smoking has negative effects on oxidative status, promoting low-density lipoprotein (LDL) oxidation and formation of lipid peroxides. We evaluated the effects of 2 different encapsulated formulas, consisting primarily of mixed juice powder concentrate, on oxidative status compared with placebo.

METHODS

This randomized, double-blind, placebo-controlled study was performed on 101 apparently healthy heavy smokers (>20 cigarettes/d, duration >10 years; median age 47 years, range 41-57 years; 54 M) before and after 3 months' supplementation. Subjects were randomized into 3 groups, well matched for sex and age: (1) placebo; (2) fruit/vegetable (FV); and (3) fruit/vegetable/berry (FVB). Analysis of oxidative status was performed on 75 (46 M) compliant subjects (>95% of assigned capsules). Changes in lipid panel parameters, oxidative-INDEX (Oxy-I, calculated on the basis of serum hydroperoxides and total antioxidant capacity measured by spectrophotometric methods), oxidized-LDL (ox-LDL; enzyme-linked immunosorbent assay [ELISA] method), and malondialdehyde (MDA; gas chromatography-mass spectrometry method) in free (fMDA), bound (bMDA), and total (tMDA = fMDA + bMDA) forms are reported. Statistical analysis was performed with R statistical software.

RESULTS

After supplementation, compared with placebo, both FV and FVB groups showed a significant decrease in total cholesterol (p < 0.05), ox-LDL (p = 0.03), and fMDA levels (p = 0.004) accompanied by a slight increase in bMDA concentrations, possibly as the result of fMDA conjugation. Moreover, a significant decrease in Oxy-I was found in both active groups compared with placebo (p < 0.001).

CONCLUSION

Intervention with both nutraceutical formulations resulted in improvement in some oxidative alterations attributed to long-term cigarette smoking.

Oxidised fish oil does not influence established markers of oxidative stress in healthy human subjects: a randomised controlled trial

Intake of fish oil reduces the risk of CHD and CHD deaths. Marine n-3 fatty acids (FA) are susceptible to oxidation, but to our knowledge, the health effects of intake of oxidised fish oil have not previously been investigated in human subjects. The aim of the present study was to investigate markers of oxidative stress, lipid peroxidation and inflammation, and the level of plasma n-3 FA after intake of oxidised fish oil. In a double-blinded randomised controlled study, healthy subjects (aged 18–50 years, n 54) were assigned into one of three groups receiving capsules containing either 8 g/d of fish oil (1·6 g/d EPA+DHA; n 17), 8 g/d of oxidised fish oil (1·6 g/d EPA+DHA; n 18) or 8 g/d of high-oleic sunflower oil (n 19). Fasting blood and morning spot urine samples were collected at weeks 0, 3 and 7. No significant changes between the different groups were observed with regard to urinary 8-iso-PGF2α; plasma levels of 4-hydroxy-2-hexenal, 4-hydroxy-2-nonenal and α-tocopherol; serum high sensitive C-reactive protein; or activity of antioxidant enzymes in erythrocytes. A significant increase in plasma level of EPA+DHA was observed in both fish oil groups, but no significant difference was observed between the fish oil groups. No changes in a variety of in vivo markers of oxidative stress, lipid peroxidation or inflammation were observed after daily intake of oxidised fish oil for 3 or 7 weeks, indicating that intake of oxidised fish oil may not have unfavourable short-term effects in healthy human subjects.

Clinical symptoms in fibromyalgia are better associated to lipid peroxidation levels in blood mononuclear cells rather than in plasma

BACKGROUND

We examined lipid peroxidation (LPO) in blood mononuclear cells (BMCs) and plasma, as a marker of oxidative damage, and its association to clinical symptoms in Fibromyalgia (FM) patients.

METHODS

We conducted a case-control and correlational study comparing 65 patients and 45 healthy controls. Clinical parameters were evaluated using the Fibromyalgia Impact Questionnaire (FIQ), visual analogues scales (VAS), and the Beck Depression Inventory (BDI). Oxidative stress was determined by measuring LPO in BMCs and plasma.

RESULTS

We found increased LPO levels in BMCs and plasma from FM patients as compared to normal control (P<0.001). A significant correlation between LPO in BMCs and clinical parameters was observed (r = 0.584, P<0.001 for VAS; r = 0.823, P<0.001 for FIQ total score; and r = 0.875, P<0.01 for depression in the BDI). We also found a positive correlation between LPO in plasma and clinical symptoms (r = 0.452, P<0.001 for VAS; r = 0.578, P<0.001 for FIQ total score; and r = 0.579, P<0.001 for depression in the BDI). Partial correlation analysis controlling for age and BMI, and sex, showed that both LPO in cells and plasma were independently associated to clinical symptoms. However, LPO in cells, but not LPO in plasma, was independently associated to clinical symptoms when controlling for depression (BDI scores).

DISCUSSION

The results of this study suggest a role for oxidative stress in the pathophysiology of fibromyalgia and that LPO in BMCs rather than LPO in plasma is better associated to clinical symptoms in FM.

Evidence of oxidative stress in temporomandibular disorders: a pilot study

Oxidative stress is involved in the pathogenesis of many conditions and is caused by free radicals in concentrations that overwhelm the natural scavenging mechanisms and cause pain and inflammation. This investigation sought to determine whether pain from temporomandibular disorders was associated with increased oxidative stress as measured by biomarkers in saliva and serum. Both salivary and serum levels of the oxidative stress biomarkers including 8-hydroxydeoxyguanosine, malondialdehyde and total antioxidant status were compared in patients with mild and severe TMJD pain and with healthy controls. These biomarkers were determined spectrophotometrically in saliva and serum from 10 high TMJD pain patients, 10 low TMJD pain patients, and 10 healthy control subjects from National Institute of Dental Research's TMJ Implant Registry and Repository. Linear and logistic regression analyses were used to evaluate the association between each biomarker and TMJD pain. The mean levels of log 8-hydroxydeoxyguanosine (saliva P < 0·0001, serum P = 0·0008), malondialdehyde (saliva P = 0·002, serum P = 0·004) and total antioxidant status (saliva P = 0·005; serum P = 0·001) achieved statistically significant differences between groups. In linear regression analysis, both salivary and serum levels of each biomarker were associated with TMJD pain. In a multivariable analysis, again, both salivary levels and serum levels were also different between groups. Salivary levels of oxidative stress ratios of 8-hydroxydeoxyguanosine, malondialdehyde and total antioxidant status were significantly different between patients with TMJD pain and controls and was comparable to that in serum. These biomarkers hold promise as a potential diagnostic and therapeutic strategy.

Lipid peroxidation in the liver of rats treated with V and/or Mg in drinking water

The effect of V(5+) and Mg treatment on spontaneous and stimulated lipid peroxidation (LPO) was studied in liver supernatants obtained from outbred 5-month-old, albino male Wistar rats. The 2-month-old animals daily received deionized water to drink (control, group I); group II - water solution of NaVO(3) (SMV) at a concentration of 0.125 mg V ml(-1); group III - water solution of MgSO(4) (MS) at a concentration of 0.06 mg Mg ml(-1), group IV - water solution of SMV-MS at the same concentrations as in groups II and III for V and Mg, respectively, over a 12-week period. Three metal salts were selected as agents that may modify the LPO process (FeSO(4), NaVO(3) and MgSO(4)). V-intoxicated rats and those treated with V and Mg in combination had higher liver spontaneous malondialdehyde (MDA) formation, compared with the control and Mg-supplemented animals. In the same groups of animals the total antioxidant status (TAS) was also significantly lowered, in comparison with the control. In the supernatants obtained from the above-mentioned groups of rats a significant increase in MDA concentration was found in the presence of exogenous 30 microm FeSO(4) as well as 30, 100, 200 and 400 microm NaVO(3), compared with groups I and III. Significantly elevated MDA production was also observed in the supernatants obtained from the rats exposed to V and Mg in combination in the presence of exogenous 100 and 200 microm MgSO(4) in comparison with the control and group III as well as in the presence of exogenous 400 and 600 microm MgSO(4) compared only with group III. In vitro treatment with 1000 microm MgSO(4 )of control liver supernatants and those obtained from group III significantly enhanced MDA level, compared with spontaneous MDA formation. The two-way ANOVA indicated that the changes in the basal MDA level and in TAS in the rats at combined V and Mg application, were not due to V-Mg interaction, but resulted from independent action of V. In addition, the three-way ANOVA revealed that the changes in LPO induced by in vitro treatment of liver supernatants with exogenous Fe or V or Mg (600, 800 and 1000 microm) were a consequence of independent action of those metals and they also resulted from the interactions between Fe(exog) and V(end) and between V(end) and V(exog). In conclusion, V consumed by the rats with drinking water at a dose of 12 mg V kg(-1) body weight per 24 h for 12 weeks decreased TAS and enhanced spontaneous LPO in the hepatic tissue, which confirms its pro-oxidant potential, was also found in in vitro conditions with regard to LPO. Mg administered to rats in combination with V, at the concentration used, neither reduced nor intensified the basal LPO, compared with V-only treated animals; however, its stimulating effect on LPO was revealed in in vitro conditions, which requires further study.

Dimethylarginines in complicated type 1 diabetes: roles of insulin, glucose, and oxidative stress

To investigate the roles of insulin, glucose, and oxidative stress on plasma asymmetric and symmetric dimethylarginine (ADMA, SDMA) levels in complicated diabetes, we studied patients with type 1 diabetes (T1D; n = 20), T1D + end-stage renal disease under hemodialysis (T1D + ESRD; n = 12), T1D + ESRD who received kidney transplant (KD; n = 16), and T1D + ESRD who received kidney-pancreas transplant (KP; n = 20) and healthy controls (n = 50). Levels of ADMA, SDMA, and free and total malondialdehyde (MDA) were increased in all patients, with the highest rises for SDMA and free MDA in T1D+ESRD. In KP, the normalized glycemia contributes to the recovery of ADMA, SDMA, and MDA levels toward normal values. From the covariance analyses, both glucose and insulin relate significantly to ADMA in T1D + ESRD (beta = +0.004, beta = -0.038, respectively) and in KP (beta = +0.032, beta = +0.032, respectively). Creatinine clearance and insulin relate to SDMA in all patient groups (beta = -0.006). Our results provide evidence for the effect of kidney-pancreas transplant on the recovery of ADMA, SDMA, and indexes of oxidative stress toward normal values. Only free MDA allows one to discriminate the magnitude of the oxidative status, as increased total MDA could also be attributable to a reduced renal function.

Free and total plasma malondialdehyde in chronic renal insufficiency and in dialysis patients

BACKGROUND

Available data about oxidative status in patients with end-stage renal disease (ESRD) or on dialysis are contradictory. The present cross-sectional study aimed to investigate the role of renal insufficiency and dialysis on lipid peroxidation. To separate the effects of uraemia from dialysis-induced stress, we enrolled 26 patients with renal insufficiency on conservative treatment (ESRD), 23 on peritoneal dialysis (PD), 30 on haemodialysis (HD) and 30 controls.

METHODS

Plasma malondialdehyde (MDA) levels, both total (tMDA) and free (fMDA), were measured as indexes of oxidative stress by gas chromatography-mass spectrometry. Bound MDA (bMDA) levels were calculated as the difference between tMDA and fMDA.

RESULTS

Total and bMDA concentrations were significantly higher in patients than in controls (ESRD > HD > PD). In PD and HD patients, fMDA levels were similar and significantly higher than in ESRD. Multivariate analysis, with tMDA, fMDA and bMDA as dependent variables, showed similar and significant tMDA and bMDA relations with residual renal function (t = -2.160, P = 0.035) and albumin (t = -2.049, P = 0.045). Erythropoietin dose affected only fMDA values (t = -2.178, P = 0.034).

CONCLUSIONS

Free and bMDA concentrations identified different MDA patterns. Bound MDA, not excreted by kidneys, accounts alone for high tMDA concentrations in ESRD patients, while both fMDA and bMDA contribute to tMDA values in dialysis patients. These findings show that increased tMDA could be indicative not only of recent lipid peroxidation, and they also highlight the importance of evaluating free, bound and total MDA in patients with reduced renal function in order to assess their oxidative status.

Comprehensive characterization of serum clinical chemistry parameters and the identification of urinary superoxide dismutase in a carbon tetrachloride-induced model of hepatic fibrosis in the female Hanover Wistar rat

Carbon tetrachloride (CCl(4)) was used to induce liver fibrosis in the rat. Using this model, we have identified changes in serum and urinary clinical chemistry parameters, and characterized histopathological lesions in the liver. Two experiments were conducted. In Experiment 1, rats were dosed at six levels of CCl(4) (0.06-0.36 ml/kg) twice weekly for 6 weeks, followed by a 6-week non-dosing recovery period (week 12). Livers were removed for histology at 6 and 12 weeks and serum parameters analysed. In Experiment 2, rats were given seven dose levels of CCl(4) (0.4-1.0 ml/kg) twice weekly for 6 weeks, followed by a 6-week recovery period (week 12); urine samples were analysed at 3, 6, 9 and 12 weeks using one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Liver fibrosis was evident at 6 weeks in Experiments 1 and 2, and the activity of serum enzymes (including alanine aminotransferase, aspartate aminotransferase and glutamate dehydrogenase) was increased. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis (Experiment 2) revealed a protein band at 18.4 kDa in urine from rats treated with CCl(4), not present in control urine, which was identified as copper/zinc superoxide dismutase (Cu/Zn SOD). Western blotting revealed that SOD was increased in urine from rats treated with CCl(4) at 3 and 6 weeks, but not at 9 and 12 weeks. We conclude that Cu/Zn SOD is a urinary marker of hepatic necrosis, but not hepatic fibrosis.

Effects of exclusive formula or breast milk feeding on oxidative stress in healthy preterm infants

BACKGROUND

Compared to formula, breast milk is considered to have superior antioxidant properties and consequently may reduce the occurrence of a number of diseases of prematurity associated with oxidative stress.

AIMS

To test whether the antioxidant properties of breast milk in healthy premature infants are different to those of formula milk by comparing vitamin E levels in milk and determining the excretion of malondialdehyde (MDA) in urine.

METHODS

Vitamin E was measured in the breast milk of 20 mothers who had given birth prematurely. Urinary MDA was measured in 10 exclusively breast milk fed and 10 exclusively formula fed healthy preterm infants receiving no vitamin supplements. MDA was measured after derivatisation with 2,4-dinitrophenylhydrazine and consecutive HPLC with UV detection.

RESULTS

Urinary MDA concentrations were consistently very low (0.074+/-0.033 microM/mM Cr and 0.078+/-0.026 microM/mM Cr in breast and formula fed infants respectively) and not significantly different between healthy breast milk and formula fed infants. Both breast and formula milk contained satisfactory levels (0.3-3.0 mg/100 ml) of vitamin E.

CONCLUSION

Antioxidant properties of both breast milk and formulae are sufficient to prevent significant lipid peroxidation in healthy premature infants.

Biomarkers of oxidative damage in human disease

Oxidative/nitrosative stress, a pervasive condition of increased amounts of reactive oxygen/nitrogen species, is now recognized to be a prominent feature of many acute and chronic diseases and even of the normal aging process. However, definitive evidence for this association has often been lacking because of recognized shortcomings with biomarkers and/or methods available to assess oxidative stress status in humans. Emphasis is now being placed on biomarkers of oxidative stress, which are objectively measured and evaluated as indicators of normal biological processes, pathogenic processes, or pharmacologic responses to therapeutic intervention. To be a predictor of disease, a biomarker must be validated. Validation criteria include intrinsic qualities such as specificity, sensitivity, degree of inter- and intraindividual variability, and knowledge of the confounding and modifying factors. In addition, characteristics of the sampling and analytical procedures are of relevance, including constraints and noninvasiveness of sampling, stability of potential biomarkers, and the simplicity, sensitivity, specificity, and speed of the analytical method. Here we discuss some of the more commonly used biomarkers of oxidative/nitrosative damage and include selected examples of human studies.

Menopause: a review on the role of oxygen stress and favorable effects of dietary antioxidants

Menopause is often accompanied by hot flashes and degenerative processes such as arteriosclerosis and atrophic changes of the skin that suggest an acceleration of aging triggered by estrogen lack. Therefore, hormone replacement therapy (HRT) has been considered the most suitable treatment for the above symptoms and processes. However, because of the possible serious side effects of HRT (especially the increased risk of thrombo-embolic accidents and breast cancer) there is a growing demand for alternative treatments of the symptoms and pathological processes associated with menopause. In agreement with the above, we review research that supports the concept that oxygen stress contributes to menopause and that some of its physiopathological effects may be prevented and/or treated improving the antioxidant defense of menopausic and postmenopausic women. Accordingly, a selection of micronutrients may be useful as a dietary supplement for protection against the decline of physiological functions caused by age-related oxygen stress. Since aging is accompanied by a progressive oxidation of the physiological sulfur pool, we emphasize the role of the vitamins B that help to maintain the GSH/GSSG ratio in its normal reduced state. Nutritional supplements should also include the key antioxidant vitamins C and E, as well as beta-carotene and the mineral micronutrients found in the oxygen radical-detoxifying enzymes glutathione peroxidase and superoxide dismutase. Moreover, the reviewed data suport the concept that other antioxidants such as lipoic acid and the precursors of glutathione thioproline (TP) and l-2-oxothiazolidine-4-carboxylic acid (OTC), as well as the soy isoflavones and the "coantioxidants" of an hydroalcoholic extract of Curcuma longa may help to prevent antioxidant deficiency with resulting protection of mitochondria against premature oxidative damage with loss of ATP synthesis and especialized cellular functions. Therefore, the administration under medical advice of synergistic combinations of some of the above mentioned antioxidants in the diet as well as topically (for skin protection) may have favorable effects on the health and quality of life of women, especially of those who cannot be treated with HR, suffer high levels of oxygen stress, and do not consume a healthy diet that includes five daily rations of fresh fruit and vegetables.

Analysis of Derivatized Biogenic Aldehydes by LC Tandem Mass Spectrometry

Lipid peroxidation has been linked to the etiology of several diseases, including Alzheimer's disease (AD). End products of this phenomenon include low molecular weight, water-soluble aldehydes, compounds that covalently modify proteins and nucleic acids, thereby altering function. Aliphatic aldehydes (C3-C10) are generated during lipid peroxidation, along with alpha,beta-unsaturated aldehydes, including acrolein and 4-hydroxynonenal (HNE). The Hantzsch reaction was used to produce heterocyclic aldehyde derivatives that can be conveniently analyzed with mass spectrometry. Liquid chromatographic analyses revealed increasing retention times from derivatized methanal to octanal. HNE derivatives were observed to elute between heptanal and octanal derivatives, while the acrolein derivatives had a retention time similar to the propanal derivative. Smaller aliphatic aldehyde derivatives fragmented in a similar manner to produce a base peak of m/z 273, while the larger derivatives yielded m/z 274 as the base peak. Acrolein and HNE derivatives fragmented in a slightly different manner compared to their aliphatic counterparts. Calibration plots of aliphatic and unsaturated aldehydes were linear (r2 >/= 0.99) in the concentration range explored (approximately 5-1500 pg on column). The LC-MS/MS methodology developed here will be used in subsequent studies to determine aldehyde concentrations for comparing age-matched controls to AD tissues from human subjects.

Dihydroxynonene mercapturic acid, a urinary metabolite of 4-hydroxynonenal, as a biomarker of lipid peroxidation

The objective of our study was to compare the information obtained through the use of three different urinary biomarkers of lipoperoxidation during the time course of a bromotrichloromethane (BrCCl3) induced oxidative stress in rats. These biomarkers were malondialdehyde (MDA) measured by LC/MS after derivatization, the isoprostane 8-iso-PGF2alpha measured by enzyme immunoassay and 1,4-dihydroxynonene mercapturic acid (DHN-MA), the major 4-hydroxynonenal urinary metabolite [1], measured by LC-MS. Male Wistar rats received a single dose of 100 microL/kg BrCCl3 per os and lipid peroxidation was estimated every day for a 4-day-period after treatment. MDA, 8-iso-PGF2alpha and DHN-MA significantly increased in response to BrCCl3 treatment for this period of time, and DHN-MA showed the main increase during the 24-48 h period after treatment.

The cyclopentenone (A2/J2) isoprostanes--unique, highly reactive products of arachidonate peroxidation

Cyclopentenone (A2/J2) isoprostanes (IsoPs) are a group of prostaglandin (PG)-like compounds generated in vivo from the free radical-induced peroxidation of arachidonic acid. Unlike other classes of IsoPs, cyclopentenone IsoPs contain highly reactive unsaturated carbonyl moieties on the prostane ring analogous to cyclooxygenase-derived PGA2 and PGJ2 that readily adduct relevant biomolecules such as thiols via Michael addition. The purpose of this review is to summarize our knowledge of the A2/J2-IsoPs. As a starting point, we will briefly discuss the formation and biological properties of PGA2 and PGJ2. Next, we will review studies definitively showing that cyclopentenone IsoPs are formed in large amounts in vivo. This is in marked contrast to cyclopentenone PGs, for which little evidence exists that they are endogenously produced. Subsequently, we will discuss studies related to the chemical syntheses of the 15-A2-IsoP series of cyclopentenone IsoPs. The successful synthesis of these compounds provides the recent impetus to explore the metabolism and biological properties of A-ring IsoPs, particularly as modulators of inflammation, and this work will be discussed. Finally, the formation of cyclopentenone IsoP-like compounds from other fatty acids such as linolenic acid and docosahexaenoic acid will be detailed.

Identification and quantification of N(epsilon)-(Hexanoyl)lysine in human urine by liquid chromatography/tandem mass spectrometry

The identification and quantification of N(epsilon)-(hexanoyl)lysine (N(epsilon)-HEL), which was found from the reactions between lipid hydroperoxide and lysine, from human urine was examined using liquid chromatography/tandem mass spectrometry (LC/MS/MS). The N(epsilon)-HEL in the partially purified urine fraction was identified using LC/MS/MS by several approaches including precursor/product ion scans. The peak found by the multiple-reaction monitoring (MRM) of the collision-induced fragmentation of N(epsilon)-HEL was clearly observed in urine, and the elution position coincided with the synthetic standard N(epsilon)-HEL. The product, estimated N(epsilon)-HEL, was absorbed by a specific antibody to N(epsilon)-HEL. Moreover, N(alpha)-HEL, one of the plausible hexanoyl adducts from the reaction between the N(alpha) moiety of L-lysine and the peroxidized lipid, was hardly detected in urine samples, suggesting that the origin of the N(epsilon)-HEL is the peroxidized lipid-modified proteins but not artificial hexanoylated L-lysine. Using the MRM technique, the amount of urinary N(epsilon)-HEL from the control subjects (observed healthy) was estimated to be 1.58 +/- 0.23 mumol/mol of creatinine. A comparative study of the urinary N(epsilon)-HEL with an oxidative stress marker, 8-oxo-7,8-dihydro-2'-deoxyguanosine, showed a high correlation (r = 0.844) between the two biomarkers. Furthermore, the quantification of N(epsilon)-HEL in the control and diabetic urines revealed that the urinary N(epsilon)-HEL from diabetic subjects (3.21 +/- 0.65 mumol/mol of creatinine) was significantly higher than that from the control subjects.

Effect of systemic vitamin C on free fatty acid-induced lipid peroxidation

OBJECTIVES

Plasma malondialdehyde (MDA), a reactive product of lipid peroxidation, may be influenced by anti-oxidant therapy. The aim of the present study was to investigate if elevated MDA as induced by increased free fatty acids (FFA) correlates with endothelial function and is affected by high doses of vitamin C.

METHODS

The study design was randomised, placebo-controlled, double blind, 2-way cross over. Plasma MDA concentrations and forearm blood flow (FBF) responses to intra-arterial acetylcholine (ACh) and glyceryl trinitrate were assessed during co-administration of vitamin C or placebo in the presence of increased plasma FFA by Intralipid/heparin infusion in 10 healthy male subjects.

RESULTS

The seven-fold rise in plasma FFA was associated with an increase in plasma MDA concentrations (r=0.7, p<0.001) and decreased FBF responses to ACh (r=-0.4, p<0.01). Co-administration of vitamin C restored the impaired reactivity of FBF to ACh but had no effect on elevated MDA concentrations.

CONCLUSIONS

Anti-oxidant vitamin C improves lipid-induced impairment of endothelium-dependent vasodilation, but does not alter MDA formation or breakdown.

Effect of blood transfusions on oxidative stress in preterm infants

OBJECTIVE

To confirm the increase in non-transferrin bound iron (NTBI) after packed red cell (PRC) transfusion and to evaluate the association with increased oxidative stress in preterm infants.

METHOD

Twenty healthy preterm infants (gestational age 28.2 (2.2) weeks; birth weight 1047 (230) g), who required blood transfusion for anaemia of prematurity were prospectively studied. Serum concentrations of NTBI, total hydroperoxides (TH), and protein SH groups, and plasma total radical trapping antioxidant capability (TAC) were measured within three hours before and after PRC transfusion. The infants were transfused with 38.6 (23) ml PRCs over 5.8 (1.0) hours, at a mean age of 43.3 (25.1) days.

RESULTS

After PRC transfusion, haemoglobin concentration increased from 9.2 (1.1) to 14.6 (1.5) g/l. Mean plasma NTBI concentration after transfusion was significantly higher (0.43 (0.45) v 2.03 (1.31) micromol/l; p = 0.001), while plasma concentrations of TH (212.3 (42.2) v 214.7 (66.3) Carr units/l) and protein SH groups (317.5 (38.8) v 353.8 (57.4) micromol/), and TAC (256.3 (36.1) v 267.1 (42.4) micromol HClO/ml) remained unchanged.

CONCLUSION

For three hours after PRC transfusion, plasma NTBI is significantly increased in preterm infants, but this is not associated with significant changes in oxidative stress.

Analytical aspects of oxidatively modified substances in sports and exercises

Despite the health-promoting effects of physical activity, exercise enhances the formation of free radicals and other reactive species in animals and humans. Numerous techniques have been established to investigate the diverse modifications of biomolecules by oxidative stress. These analytical procedures include different methods, ranging from simple photometric assays to a combination of chromatographic methods with mass spectrometry. We summarize briefly those analytical techniques of oxidative damage to biomolecules that have been applied to the investigation of oxidative stress during exercise.